The mechanism of plasmapause formation based on interchange instability and a Kp-dependent magnetospheric electric field model, enables us to determine the position of the plasmapause as a function of Kp and local time. We illustrate here how this physical mechanism is able to account for the formation of shoulders like those observed by EUV on IMAGE. A wide variety of other structures observed by IMAGE like tails (also called plumes), and notches are also obtained with this mechanism for the formation of a "knee" in the high altitude cross-L distribution of the cold plasma density distribution.